Table 2.

Kinetic parameters ($\mu$M,$\mu$M/h,/h)

Velocity	Parameter	Model value	Literature value	References
$V_{\mathrm{AADC}}$	Aromatic amino acid decarboxylase
	$K_m$	160	160	[23]
	$V_{\mathit{max}}$	400		*
$V_{\mathrm{CATAB}}$	Catabolism of serotonin
	$K_m$	95	94–95	[24, 25]
	$V_{\mathit{max}}$	4000		*
$V_{\mathrm{DRR}}$	Dihydropteridine reductase
	$K_{bh2}$	100	4–754	[26, 27]
	$K_{\mathrm{NADPH}}$	75	29–770	[28–30]
	$V_{\mathit{max}}^f$	5000		*
	$K_{bh4}$	10	1.1–17	[29, 31]
	$K_{\mathrm{NADP}}$	75	29–770	[28–30]
	${V_{\mathit{max}}}^b$	3		*
$V_{\mathrm{MAT}}$	Vesicular monoamine transporter
	$K_m$	.2	.123–.253	[32, 33]
	$V_{\mathit{max}}$	1230		*
$V_{\mathrm{POOL}}$	Linear exchange between trp and pool
	$k_{\mathit{topool}}$	9		*
	$k_{\mathit{frompool}}$	0.6		*
$V_{\mathrm{SERT}}$	Serotonin transporter
	$K_m$	.06	0.05–1	[34]
	$V_{\mathit{max}}$	250		*
$V_{\mathrm{TPH}}$	Tryptophan hydroxylase
	$K_{\mathit{trp}}$	40	40	[35]
	$K_{bh4}$	20	20	[35]
	$V_{\mathit{max}}$	278		*
	$K_i$ (substrate inhibition)	1000	970	[35]
$V_{\mathit{trpin}}$	Neutral amino acid transporter
	$K_m$	330	64	[36]
	$V_{\mathit{max}}$	700		*
$V_{\mathrm{U}2}$
	$K_m$	.17	0.17	[37, 38]
	$V_{\mathit{max}}$	14		[37, 38]
Linear diffusion or catabolism
	$k_{\mathit{trp}}^{\mathit{catab}}$	2		*
	$k_{\mathit{cht}}^{\mathit{leak}}$	1		*
	$k_{\mathit{ght}}^{\mathit{leak}}$	1		*
	$k_{\mathit{hiaa}}^{\mathit{catab}}$	1	.82	[39]
	$k_{\mathit{pool}}^{\mathit{catab}}$	1		*
	$k_{\mathit{eht}}^{\mathit{rem}}$	40		*
The serotonin autoreceptor
	$G_{\mathit{ht}}^{\mathit{tot}}$	10		*
	$T_{\mathit{ht}}^{\mathit{tot}}$	10		*
	$B_{\mathit{ht}}^{\mathit{tot}}$	10		*
	$k_1$	20		*
	$k_2$	200		*
	$k_3$	30		*
	$k_4$	200		*
	$k_5$	36000		*
	$k_6$	20000		*
	${\beta }_1$	1		*
	${\beta }_2$	1		*
	${\beta }_3$	1		*
The histamine $H_3$ receptor
	$G_{\mathit{ha}}^{\mathit{tot}}$	1		*
	$T_{\mathit{ht}}^{\mathit{tot}}$	60		*
	$B_{\mathit{ht}}^{\mathit{tot}}$	10		*
	$k_7$	4.32		*
	$k_8$	1.296		*
	$k_9$	14.4		*
	$k_{10}$	25.92		*
	$k_{11}$	432		*
	$k_{12}$	1440		*
Other constants (varied in some experiments)
	NADP	26		*
	NADPH	330		*
	btrp	96		*
	eha	1.39		*

*See text